焙烧镁铝水滑石的制备及其对水中Cl-和SO42-的吸附特性

采用共沉淀法制备了n(Mg):n(Al)=3:1的镁铝水滑石(LDH),进一步通过焙烧得到改性产物LDO,用XRD与FT-IR对LDO进行了表征,系统研究了其对水中Cl-和SO42-的吸附特性。结果表明:焙烧温度为400℃时,LDO对Cl-和SO42-的吸附量较焙烧前分别提高了75.00%和78.20%;pH值在4~10之间,LDO对Cl-和SO42-的吸附量基本无变化;LDO对Cl-和SO42-的吸附分别符合准一级、准二级动力学模型,吸附等温线均可以用Langmuir方程来描述,最大吸附量分别为61.88和227.79 mg/g。LDO对不同浓度的盐渍土洗盐废水的吸附研究结果表明,LDO对洗盐废水中Cl-和SO42-的去除具有较好的效果。LDO投加量相同情况下,Cl-和SO42-浓度分别为60.71和50.03 mg/L时,LDO对Cl-和SO42-的吸附量分别为16.97和22.85 mg/g;当废水中Cl-和SO42-浓度分别为585.75和513.08 mg/L时,LDO对Cl-和SO42-的吸附量分别为0.89和112.47 mg/g。以上研究结果表明,利用LDO处理轻度的氯化物(氯化物硫酸盐)型盐渍土洗盐废水和中度硫酸盐(硫酸盐氯化物)型盐渍土洗盐废水时,吸附效果较好。

Synthesis of calcinations modified Mg-Al hydrotalcite and its adsorption properties for Cl-and SO42-in water

In the present study, Mg-Al layered double hydroxide (LDH) (n(Mg):n(Al)=3:1) was prepared via a co-precipitation method, and then was calcined to obtain the modified product layered double oxide (LDO).The structure of the LDO was examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).Afterwards, the adsorption properties of the LDO for Cl- and SO42- in water were researched systematically.The results showed that the adsorption capacities of the modified product (LDO) increased by 75.00% and 78.20% compared to the LDH when the calcination temperature was 400℃.When the initial pH value of the solution changed in the range from 4 to 10, the adsorption capacities of the LDO for Cl- and SO42- changed slightly.The results also showed that the adsorption capacities of the LDO for Cl- and SO42- conformed to the pseudo-first-order and pseudo-second-order adsorption kinetic models, respectively, and both of the adsorption processes were fitted well with the Langmuir equation.The maximum adsorption capacities of Cl- and SO42- were 61.88 and 227.79 mg/g, respectively.Subsequently, the LDO was further used to adsorb the Cl- and SO42- in saline soil washing wastewater.The LDO exhibited a satisfactory adsorption capacity.When the concentrations of Cl- and SO42- were 60.71 and 50.03 mg/L, the adsorption capacities were 16.97 and 22.85 mg/g, respectively.When the concentrations of Cl- and SO42- were 585.75 and 513.08 mg/L, the sorption capacities were 0.89 and 112.47 mg/g.The above results indicated that the LDO can be used to deal with mild chlorides (chloride sulfate) and moderate sulfates (sulfate chloride) in saline soil washing wastewater.